In recent years, technology known as OpenFlow has been proposed (see Non Patent Literature (NPL) 1 and 2). In OpenFlow, communication is taken as end-to-end flow, and path control, failure recovery, load balancing, and optimization are performed on a per-flow basis. An OpenFlow switch as specified in Non Patent Literature 2 is provided with a secure channel for communication with an OpenFlow controller, and operates according to a flow table in which appropriate addition or rewriting is instructed by the OpenFlow controller. In the flow table, for each flow there are definitions of sets of match conditions (Match Fields) for collation with packet headers, flow statistical information (Counters), and instructions (Instructions) that define processing content (refer to “4.1 Flow Table” in Non Patent Literature 2).
For example, when an OpenFlow switch receives a packet, a search is made for an entry having a match condition (refer to “4.3 Match Fields” in Non Patent Literature 2) that matches header information of the received packet, from the flow table. As a result of the search, in a case where an entry matching the received packet is found, the OpenFlow switch updates the flow statistical information (Counters) and also implements processing content (packet transmission from a specified port, flooding, dropping, and the like) described in an Instructions field of the entry in question, for the received packet. On the other hand, as a result of the search, in a case where an entry matching the received packet is not found, the OpenFlow switch transmits a request for entry setting, to the OpenFlow controller via the secure channel, that is, a request (Packet-In message) to transmit control information for processing the received packet. The OpenFlow switch receives a flow entry determined by processing content and updates the flow table. In this way, the OpenFlow switch preforms packet forwarding using entries stored in the flow table as control information.
Patent Literature (PTL) 1 discloses an optical network system provided with optical path establishing means, and configured from a plurality of optical edge routers that connect an external IP network to an optical network, and a plurality of optical cross-connect devices provided with switching means for connecting between the optical edge routers by optical paths on an optical path basis.
[PTL 1]
    International Publication No. WO2004/071033[NPL 1]    Nick McKeown and seven other authors, “OpenFlow: Enabling Innovation in Campus Networks”, [online], [Search performed on Jul. 13, 2012], Internet <URL: http://www.openflow.org/documents/openflow-wp-latest.pdf>[NPL 2]    “OpenFlow Switch Specification” Version 1.1.0. Implemented (Wire Protocol 0x02), [online], [Searched performed on Jul. 13, 2012], Internet <URL:http://www.openflow.org/documents/openflow-spec-v1.1.0.pdf>